Abstract
TRANSYT is a computer program that simulates and optimizes the traffic flow in a network with controlled intersections. The program has shown to be a good study tool and a good instrument for the design of control schemes. The program has some restrictions because it works with fixed traffic volumes and fixed control schemes. It is possible, however, to construct traffic dependant modifications, for instance to give absolute priority to vehicles of public transport. This paper describes some possibilities and restrictions of TRANSYT.